Ethanol Blend Race Fuel

[bobdar]

Thinking about trying Sunoco GT or GT+ in my 9.3:1 CR road course racer. Both are unleaded and use ethanol for octane boost; GT has 3.5% O2, GT+ 4.5% (by weight). Ethanol is interesting, the BTU value is lower than gasoline, but when retuned for the 9:1 stoichiometry, the total energy is about equal to gasoline. The interesting part is the latent heat of evaporation (~2.5 X gasoline) and the potential for charge cooling and VE increase. Any experience out there??

[oldhead]

This is not the answer yoy want but as a point of interest when I go from pump gas to race gas on the dyno I always loose 15 hp.,Then when I go up with the timing I get the 15 back(This is with boost) OLDHEAD

[Joe Mendelis]

All the Daytona Prototype heads I do that run on that fuel come back with the ports filled with nasty residue from the ethanol. The ports have to get that junk cleaned out every rebuild.

[bobdar]

Interesting about the residue. I had heard the opposite, that the ethanol tends to burn clean and wash down the valves. Still curious if anyone has tried to optimize with either of these fuels, and what their opinions are.

[T RICK]

What is the ethonal contentent of the fuel in percentages 10, 15, 20% ?

[bobdar]

Well, Sunoco's not exactly eager to share that info, but they do advertise the O2% by weight!

Since ethanol is 35% O2 by weight, I figure that GT (3.5% O2) is 10% ethanol, and that GT+ (4.5% O2) is about 13%, assuming the main oxygen contributor is the ethanol. GT+ used MBTE for some time, but that is now phased out and replaced with ethanol for octane boost. GT is 100 octane and street-legal, whereas GT+ is 104 and is not street-legal, probably because is has more than 10% ethanol (the legal limit).

My question remains, does the extra cooling (higher latent heat of evaporation) make more ponies???

[Grocerius Maximus]

Screw MTBE, use propylene oxide!

[OldSStroker]

All the Daytona Prototype heads I do that run on that fuel come back with the ports filled with nasty residue from the ethanol. The ports have to get that junk cleaned out every rebuild.

What brand lof DP heads do you do, Joe? P? L? or ?

When the DP's were at Watkins Glen with the NASCAR race, I didn't notice two Sunoco fuels. Does Cup Sunoco contain ethanol?

Are you willing to talk DP heads?

[quickd100]

Just pick up some E85, (85% ethanol) minumum 105 octane. It's .20 to .80 cents a gallon cheaper than the low grade regular unleaded.

[T RICK]

Forgot to ask do you use pump gas in Denver and do you run carbs or FI? My point will be Denver front range gas has had oxy fuel for a long time and it has been ethonal for years and with carbs vapor lock was real common. We used a simple alchoal test kit from NAPA and found amonts well over 20% Splash blending is a problem in Denver except for the Conaco refinery is the only computer blending done there. As far as making more power I will say no because you will jet up to correct for the o2 in the fuel and the cooling you are looking for will be very negligable with this small amount in the blend. Had enough trouble with ethonal at that altitude that I pesonaly would stay away from it and use race gas for stability.

[Joe Mendelis]

All the Daytona Prototype heads I do that run on that fuel come back with the ports filled with nasty residue from the ethanol. The ports have to get that junk cleaned out every rebuild.

What brand lof DP heads do you do, Joe? P? L? or ?

When the DP's were at Watkins Glen with the NASCAR race, I didn't notice two Sunoco fuels. Does Cup Sunoco contain ethanol?

Are you willing to talk DP heads?

Cup cars run Supreme. It's a leaded fuel. It uses lead mostly to get it's octane rating. GT fuels use ethanol to raise octane. You look at Tony Stewarts heads after a race and they have a blue haze that can be wiped out with a paper towel. Angelelli's heads need to be scotch-brited to get them clean. I blame it on the ethanol in the fuel 100%. The Supreme; if it has ethanol, doesn't leave a trace of soot in the ports.

DP heads? What are you looking for?

[BigPurp]

Just pick up some E85, (85% ethanol) minumum 105 octane. It's .20 to .80 cents a gallon cheaper than the low grade regular unleaded.

Yes but with the stochiometric ratio you will burn roughly 60% more to achieve the proper a/f ratio. You don't work off 14:1ish like with gasoline, it would be closer to 7.

[hotrod]

I live in Denver and have run 30% - 100% E85 for almost 2 years with no problems at all in a Subaru WRX. It LOVES the fuel. Very nice improvement in mid range torque and drivability along with a noticable power gain across the board.

Ethanol leaves no residue when it burns!!

If you are seeing a residue in the intake manifold, heads its coming from something else other than the ethanol in the fuel. Give us a bit more info on the appearence of the residue you are seeing.

The Sunoco GT+ and I believe the GT100 uses MMT as an octane enhancer. MMT leaves an orange coating that looks a bit like rust.

The ethanol is simply added as an oxygenate and to speed the burn rate slightly, its octane effect in the small amounts added will only be 1 - 2 octane numbers.


Denver has had oxygenated fuels (mostly with ethanol) since the fall of 1988 as part of our pollution control regulations. It was also added to gas earlier than that to lower the cost of high octane fuel when they started taking lead out of pump gas. There were some problems in the late 1970s' but have not seen any issues with fuel blending here in almost 20 years. If you have vapor lock problems here, it is due to poor heat managment in the engine comparment and poor routing of the fuel lines. It is common for cars that have basic problems to have vapor lock issues on the first hot days when we are still running winter blend gasoline.

The higher vapor pressure fuels used in the winter are to ensure good cold weather starting. Not an issue from ethanol, it also occured before ethanol was common in our fuels.

I've run carburated engines up here for the better part of 38 years and never had a vapor lock problem that was not traceable to basic setup issues, like a fuel line that was poorly routed. This includes 58 Chryser Hemi's on the street, Chrysler 440's, Chrysler 383's, AMC 401's to name a few of the big block V-8's.

I currently hold the local record up here for a stock turbo WRX --- that run was made on a mixture of Sunaco GT+ and 30% E85. My trap speed is almost 3 mph faster than the next fastest stock turbo WRX.

Try fuel ethanol (E98) or (E85) I think you will be pleasently surprised.

My question remains, does the extra cooling (higher latent heat of evaporation) make more ponies???

Yes --- it also is due to differences in how the fuel burns ( ie higher burn speed, less work during the compression stroke etc.)

bobdar --- if you like PM me and I can give you more detail info.

Yes but with the stochiometric ratio you will burn roughly 60% more to achieve the proper a/f ratio. You don't work off 14:1ish like with gasoline, it would be closer to 7.

Stoich on E85 is approximately 10:1 AFR you need to increase fuel flow approximately 27% - 30 % on straight E85 to get about the same effective mixture you had on straight gasoline. An AFR of 7:1 is about right for max power rich on pure ethanol.

Code: Select all

Fuel                      AFRst     FARst     Equivalence   Lambda 
----                      -----     -----       Ratio       ----- 
=======================--==================================== 

Gasoline   stoich          14.7    0.068       1           1 
Gasoline Max power rich    12.5    0.08        1.176       0.8503 
Gasoline Max power lean    13.23   0.0755      1.111       0.900 

=======================--==================================== 

E85 stoich                 9.765    0.10235    1          1 
E85 Max power rich         6.975    0.1434     1.40       0.7143 
E85 Max power lean         8.4687   0.118      1.153      0.8673 


=======================--==================================== 

E100 stoich                9.0      0.111      1          1 
E100 Max power rich        6.429    0.155      1.4        0.714 
E100 Max power lean        7.8      0.128      1.15       0.870 


=======================--====================================

Larry